Surface cleaning apparatus

ABSTRACT

Our invention relates to surface-cleaning apparatus having a housing which is adapted to hold a body of liquid that generates foam when air bubbles therethrough. A surface-contacting member, which is carried by the housing and is movable over a surface, functions to distribute foam. Air under pressure is delivered from a source of supply to the inlet of an air line which is located exteriorly of the housing. The outlet of the air line is located within the housing at its bottom and connected to a device to form air bubbles which rise through the body of liquid to generate foam. Foam is conducted through a passageway from the upper part of the housing to the surface-contacting member. A conventional household suction cleaner can be conveniently used as the source of supply of air under pressure. In order to generate foam in the apparatus which is relatively dry and not excessively moist, the air inlet end of the air line is connected to the blowing end of suction cleaner by a coupling which may be referred to as a bypass valve and functions to divert and bleed to the atmosphere a major portion of the air discharged from the blowing end of the suction cleaner. In this way the rate at which air under pressure is delivered to the bottom of the housing through the air line will be correct to generate foam that is relatively dry.

United States Patent 72] inventors Bengt 010g Crener Taby; Stig Carl-Oskar Ernolf, Sollentuna, both of Sweden [21] Appl. No. 10,763

[22] Filed [45] Patented [73] Assignee Feb. 12, 1970 Jan. 11, 1972 Aktiebolaget Electrolux Stockholm, Sweden [3 2] Priority Feb. 13, 1969 [33] Sweden [31] 1973/1969 [54] SURFACE CLEANING APPARATUS 3 Claims, 8 Drawing Figs.

[52] US. Cl 15/321,

15/323, 15/339 [51] 1nt.Cl A471 11/34 [50] Field of Search 15/320,

OTHER REFERENCES German Printed Appl. 1208458, W. Appel, l5 321, 1- 1966 German Printed Appl. 1207564, G. Konig, 15- 321, 12- 1965 Primary Examiner-Walter A. Scheel Assistant Examiner-C. K. Moore Att0rneyEdmund A. Fenander ABSTRACT: Our invention relates to surface-cleaning apparatus having a housing which is adapted to hold a body of liquid that generates foam when air bubbles therethrough. A surface-contacting member, which is carried by the housing and is movable over a surface, functions to distribute foam. Air under pressure is delivered from a source of supply to the inlet of an air line which is located exteriorly of the housing. The outlet of the air line is located within the housing at its bottom and connected to a device to form air bubbles which rise through the body of liquid to generate foam. Foam is con ducted through a passageway from the upper part of the housing to the surface-contacting member. A conventional household suction cleaner can be conveniently used as the source of supply of air under pressure. In order to generate foam in the apparatus which is relatively dry and not excessively moist, the air inlet end of the air line is connected to the blowing end of suction cleaner by a coupling which may be referred to as a bypass valve and functions to divert and bleed 'to the atmosphere a major portion of the air discharged from the blowing end of the suction cleaner. In this way the rate at which air under pressure is delivered to the bottom of the housing through the air line will be correct to generate foam that is relatively dry.

' PATENTED JMH I 1972v SHEET 1 [1F 2 in mg SURFACE CLEANING APPARATUS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to surface-cleaning apparatus in which foam is generated in a body of cleaning liquid by bubbling air therethrough, the foam being conducted from a space above the liquid surface level of the liquid body to a surface contacting member which is movable over a surface and functions to distribute the foam.

2. Description of the Prior Art In known surface-cleaning apparatus air bubbles to generate foam in a body of liquid are formed from a stream of air supplied under pressure from a conventional household suction cleaner. With this arrangement foam is generated very rapidly which causes liquid to be carried away with the foam. This is objectionable because the generated foam is extremely moist. After such foam has been distributed on a surface like a rug, for example, the rug becomes wet which is not desirable. This means that the length of time for the rug to dry becomes longer which in turn increases the overall length of time to perform the entire cleaning process. Also, the final cleaning result is impaired when cleaning is effected with foam that is excessively moist.

Filters have been employed to remove moisture from foam passing therethrough. While this way of removing moisture from foam has been successful to a certain degree, this means that additional expense is encountered by providing filters in the surface-cleaning apparatus.

SUMMARY OF THE INVENTION It is an object of our invention to provide an improved surface cleaning apparatus for producing foam that is relatively dry and not excessively moist. We accomplish this by forming air bubbles in the bottom of a body of liquid from a stream of air under pressure which is delivered thereto through an air line having its inlet end connected to a source of supply of air under pressure and regulating the quantity of air supplied through the air line to prevent liquid being carried away with the foam so that it will not be excessively moist. When a conventional household suction cleaner is employed as the source of supply of air under pressure, the quantity of air supplied through the supply line can be regulated by employing a coupling to connect the air inlet end of the air line to the blowing end of the suction cleaner. Such coupling, which may be referred to as a bypass valve, functions to divert and bleed to the atmosphere a major portion of the air that otherwise would flow from the blowing end of the suction cleaner through the air line.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of surface cleaning apparatus which embodies our invention and a suction cleaner for supplying air under pressure thereto;

FIG. 2 is a vertical sectional view of the apparatus shown in FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view of details illustrated in FIG. 2;

FIG. 4 is a sectional view taken at line 4-4 of FIG. 2;

FIG. 5 is a front elevational view of parts shown in FIGS. 1 and 2;

FIG. 6 is a top plan view of the parts shown in FIGS. 1, 2 and FIG. 7 is a perspective view of a portable storage receptacle and filling stand for the apparatus seen in FIGS. 1 and 2; and

FIG. 8 is a view, partly in section, illustrating the manner in which the apparatus of FIGS. 1 and 2 is positioned in the receptacle and stand of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, the surface cleaning unit comprises surface cleaning apparatus 10, a flexible hose 11 for supplying air under pressure to the apparatus 10, and a suction cleaner [2 which serves as a source of supply of air delivered under pressure to the hose II. The suction cleaner 12 includes a casing 12a having an end cover 13f provided with an outlet 13g to which the hose 11 is adapted to be removably secured by a coupling 13. Air is drawn into the casing 12a through an inlet, which is at the end of the casing opposite the end cover 13f, by a suitable motor fan unit (not shown) disposed therein. Air discharged under pressure from the outlet 13g serves as a source of supply of air under pressure for the surface cleaning apparatus 10.

In FIGS. I to 6 of the drawing, the invention has been shown in connection with surface cleaning apparatus [0 which com prises an elongated multisided housing 10a which, as illustrated, is triangular in cross section and includes a large bottom section 10b and a smaller top section 100. An opening 15 adapted to be closed by a cap 15a is provided at the top of the large bottom section 10b of the housing 10. The housing 10 is adapted to be filled at the opening 15 with a suitable cleaning agent capable of generating foam when air bubbles therethrough, as will be explained presently.

When the housing 10 is viewed with its longitudinal axis in a vertical or upright position, it will be seen that the bottom and sidewall thereof are connected by a flat wall section 10d which, in a true sense, forms a part of the sidewall of the housing. However, when the housing 10a is in its inclined operating position seen in FIG. 2 the fiat wall section 10a constitutes the lowest part of the housing for a useful purpose which will be described presently.

The housing 10a at its upper end is provided with an opening Me which is closed by a cap or cover 10f threadedly connected thereto. The apparatus 10 is provided with a handle 9 which is connected to the cover 10f by a coupling 9a. The handle 9 is hollow and connected to the hose 11 to receive air under pressure from the suction cleaner 12. An opening 28 is provided in the wall of the handle for a purpose to be described hereinafter.

An open top vessel 18 is fixed within the upper part of the housing 10a by the cover 10f. A second smaller open top vessel 8 nests within the vessel 18 and forms a cover therefor, the second vessel also being fixed within the upper part of the housing 10a by the cover 10f. The second vessel 8 defines a chamber 8a which receives air under pressure from the hollow handle 9. Such air flows from chamber 8a through a conduit 7 which extends downward within the housing 10a to the fiat wall section 10d at the bottom thereof. The lower end of the conduit 7 is connected to a nozzle 14 having a plurality of small openings to subdivide the air discharged therethrough which then bubbles upward through the body 6 of cleaning agent in the bottom half of the housing 10a.

The air bubbling upward in the body 6 of cleaning agent generates foam which is forced upward in the upper part of the housing above the liquid level therein. The foam is forced through openings 17 in the sidewall of the vessel 18 into the interior 18a thereof and passes downward therefrom through a bottom opening 18b into the upper end of a conduit 16 which is disposed within the housing 10a. The lower open end of the conduit 16 is connected to the bottom of the housing 100 at an opening therein which defines a passageway 16a for discharging the foam into a chamber 5 formed at the underside of a base 4 by a wall part thereof and a plate 40 fixed thereto.

An elongated hollow roller or surface contacting member 23 is journaled at 23a to the sidewall of the base 4 and provided with spaced ridges 26 which extend lengthwise thereof and are of spiral form. The plate 40 extends over the roller 23 and is provided with openings 4b through which foam can pass from the chamber 5 onto the peripheral surface of the roller.

Elongated brushes 24 and 25 are fixed to the base 4 at opposite sides of the roller 23. The tips of bristles 24a and 25a of the brushes are adapted to frictionally engage a surface 3 being cleaned, such as a carpet, for example, at the same time the roller 23 is being moved back and forth by the handle 9 over the surface in physical contact therewith.

In accordance with our invention, in order to generate foam in the surface cleaning apparatus which is relatively dry and not excessively moist, the coupling device 13, which may be referred to as a bypass valve, is so constructed and formed that all of the air under pressure is not delivered from the suction cleaner 12 to the cleaning apparatus. We accomplish this by providing a partition 13a in the coupling device to form first and second passageways 13b and 130 into which air is discharged from the suction cleaner.

Air discharged into the first passageway 13b flows therefrom through the hose 1] to the hollow handle 9. Air discharged into the passageway 13c flows through openings 13a in the coupling 13 to the ambient air. In a broad sense a major portion of the air discharged from the suction cleaner is bled from the main airstream and vented directly to the body of atmospheric air enveloping the coupling 13. ln accord with our invention, therefore, we only make use of a small portion of the airstream that is necessary to generate foam that is relatively dry not excessively moist.

The opening 28 in the hollow handle 9 provides a convenient arrangement for controlling the operation of the surface cleaning apparatus 10. When it is desired to operate the apparatus 10 an operator holding the manipulating handle 9 simply places a finger over the opening 28 whereby air under pressure can then flow through conduit 7 to the nozzle 14. When the opening 28 is not closed, air under pressure is discharged therethrough to the atmosphere because the body 6 of liquid cleaning agent in the housing 10a offers greater resistance to air flowing thereto than the resistance offered to flow of air at the opening 28.

By providing the flat portion 10d at the bottom part 10c of the housing 10a and locating the nozzle 14 closely adjacent to this flat portion, air bubbles will pass through the entire mass of the liquid body 6 and it will be effectively used to generate foam.

Since the opening 15 for introducing liquid cleaning agent into the housing 10a is about midway between the top and bottom thereof, the liquid surface level 6a of the liquid body 6 can never be above the opening 15. This means that the foam generated in the housing 101: must rise therein above the liquid surface level 6a through a vertical height which is approximately one-half the height of the housing.

The foam, which slowly rises in the housing 10a due to the slight positive pressure therein, in this way is subjected to a drying action in the housing. This drying action, in addition to supplying air under pressure at such a rate that the foam generated will be relatively dry and not excessively moist, results in supplying to the surface being cleaned foam which is practically dry. The foam passing from the chamber 5 and openings 4h onto the roller 23 is effectively distributed on the surface 3 by the back and forth movement imparted to the roller 23.

Additional advantages are realized by employing the coupling 13 to connect the blowing end of the suction cleaner l2 and the hose 11. Even when the hose 11 has a sharp bend and more or less obstructs the flow of air therethrough, the major portion of the main airstream diverted through the openings 13d to the atmosphere will prevent complete blocking of the flow of air through the suction cleaner 12, so that overloading of the motor fan unit and objectionable overheating of the motor will be avoided. Further, the collar 13s at the air inlet end of the coupling 13 forms a unitary part thereof for mounting the coupling at the air outlet or blowing end 133 of the cleaner 12. The coupling 13, which constitutes an independently movable component of the surface cleaning apparatus, is hollow and has an outer wall. Each of the passageways 13b and 130 is defined by the outer wall of the coupling and the axially extending partition 13a and has an air inlet at the end 13:: of the coupling connected to the air outlet 13g of the cleaner. Since the suction cleaner 12 is ofa conventional type having a dust collecting receptacle therein the air discharged from the outlet 13g will be substantially free of dust. Hence, the air supplied through the air inlet line 11 to the housing 10 will be substantially clean air.

A sleeve 19 of annular form is movable axially within the interior 18a ofthe vessel 18. When the surface cleaning apparatus 10 is upright, as shown in FIG. 2, the sleeve 19 is at the bottom of the vessel 18 and the openings 17 are not closed. If the apparatus 10 should be inverted the sleeve 19 will move axially of the vessel 18 and close the openings 17. Further, the top and bottom parts 101: and of the housing 10 are of such shape and size that, when the apparatus 10 is placed on its side, the liquid surface level of the liquid body 6 will be below all of the openings 17. In this way liquid cannot flow through the tubing 16, passageway 16a, chamber 5 and openings 4a to cause objectionable wetting of the surface being cleaned.

ln the event the coupling 13 is connected to the suction inlet of the suction cleaner instead of the outlet 13g at the blowing end of the cleaner, the suction effect produced in the hose 11 cannot be transmitted to the body 6 of cleaning liquid in the housing 10a. As seen in H68. 2 and 3, a flexible diaphragm 20 having an aperture 20a is fixed within the cover 10f. When air under pressure normally is supplied through the hose 11 to the housing 10a, the opening 28 being closed by the operator's finger, the diaphragm 20 assumes the position shown in FIG. 3 and air can flow through the aperture 20a which is open. However, the diaphragm 20 will flex toward a wall part 10g within the cover 10f and close the aperture 20a when the opening 28 is closed by the operators finger and the diaphragm is subjected to suction. Hence, liquid can never be sucked from the housing 10a and flow to the suction cleaner 12 when the coupling inadvertently is connected to the suction inlet of the cleaner.

Further, one or more devices 21 and 22 can be employed to produce high pitch sounds which will warn an operator that the hose 11 of the surface cleaning apparatus 10 has not been connected to the blowing outlet 13!; of the suctioncleaner 12. The warning device 21 comprises a thin reedlike flexible member 21a held between an apertured disk 21b and apertured plug 21c in the cover or cap 10f of the housing l0a.-The reedlike member 21a is provided with a very small opening (not shown). When the diaphragm 20 flexes to close the opening 20a with the hose ll inadvertently connected to the suction inlet of the cleaner l2 and the opening 28 is closed by the operators finger, the reedlike member 21a will be subjected to the full suction effect of the cleaner and air sucked inward through the very small opening therein will cause the member 210 to vibrate and produce an audible sound and serve as a warning signal.

During normal operation of the surface cleaning apparatus 10, when the diaphragm 20 is in the position shown in FIG. 3 and the opening 28 is closed by the operator's finger, the air flowing past the reedlike member 21a will not cause the latter to produce an audible sound. This is so because the member 210 under these conditions is located for all practical purposes in a dead end space through which there is no rapid movement of air.

The warning device 22 comprises a U-shaped cup 22a provided in the end of the handle 9. The bottom of the cup is formed with an opening through which extends a neck portion 22b of a part 220 disposed in the cup 22a. A disk 22d is fixed to the outer extremity of the neck portion 22b. During normal operation of the surface-cleaning apparatus 10 when air under pressure is delivered to the hollow handle 9 and the opening 28 is closed by the operator's finger, the disk 22d is forced toward the opening at the bottom of the cup 22a and closes the latter. However, when the hose 11 inadvertently is connected to the suction inlet of the cleaner and the opening 28 is closed by the operator's finger, the suction effect will cause the disk 22d to move toward the opening 28 and uncover the opening in the bottom of the cup 22a whereby air passing therethrough will produce an audible sound.

A portable storage receptacle 27 is illustrated in FIG. 7 in which the surface-cleaning apparatus 10 can be stored in the manner shown in FIG. 8. The receptacle 27 is provided with compartments 27a and 27b to receive the hose 11 and a bottle 27c adapted to hold cleaning liquid. In FIG. 5 it will be seen that the receptacle 27 can also serve as a stand to hold the surface cleaning apparatus in the correct vertical position when filling the housing 100 with cleaning liquid.

We claim:

1. Surface-cleaning apparatus comprising a. a source of supply of air under pressure comprising a movable tank-type suction cleaner having an inlet and outlet for air, the outlet serving as the blowing end of said cleaner,

structure providing a housing adapted to hold a body of cleaning liquid possessing such physical properties that it will generate foam responsive to air bubbling therethrough,

c. surface contacting means which is carried by said housing structure and movable over a surface for distributing foam thereon,

d. an air line having an air inlet exteriorly of said housing and an air outlet within said housing at the bottom thereof,

e. means including a bypass valve for conducting air under pressure from the outlet of said cleaner to the inlet of said air line,

f. means at the outlet of said air line for subdividing the air under pressure to form air bubbles which rise through the body of liquid to generate foam,

g. vertically extending conduit means defining a passageway having its upper end in communication with the upper part of said housing and its opposite lower end communicating with said surface contacting means for flowing thereto foam from the upper part of said housing,

h. the inlet of said air line being connected to said bypass valve,

. said bypass valve having one passageway which receives a major portion of the air discharged from the suction cleaner outlet and diverts such air to the atmosphere and another passageway which receives the lesser remaining portion of the air discharged from the suction cleaner outlet and conducts such air to said air line,

j. a valve in said air line,

k. said valve including means defining a seat and a valve movable between a closed position at said seat and an open position removed therefrom, and

I. said valve being in its open position when air under pressure is delivered to the inlet of said air line from the outlet of said suction cleaner, and, when the inlet of said suction cleaner inadvertently is connected to the inlet of said air supply line, said valve moving to its closed position responsive to flow of air in said air line toward the inlet end thereof.

2. Surface-cleaning apparatus comprising a. structure providing a housing adapted to hold a body of cleaning liquid possessing such physical properties that it will generate foam responsive to air bubbling therethrough,

b. surface contacting means which carried by said housing structure and movable over a surface for distributing foam thereon,

c. an air line having an air inlet exteriorly of said housing and an air outlet within said housing at the bottom thereof,

d. means connected to the inlet of said air line for delivering thereto air under pressure from a source of supply,

e. means at the outlet of said air line for subdividing the air under pressure to form air bubbles which rise through the body of liquid to generate foam,

f. vertically extending conduit means defining a passageway having a region at its upper end in communication with the upper part of said housing and its opposite lower end communicating with said surface contacting means for flowing thereto foam from the upper part of said housing, g. means associated with said air line for diverting and bleeding therefrom a portion of the air adapted to be supplied thereto under pressure from the source of supply, h. said vertically extending conduit means including an en larged portion at its upper end which defines a vessel having a top cover and a sidewall which is apertured and constitutes said region in communication with the upper part of said housing, and

i. a member of annular form within said vessel which is adjacent to said sidewall thereof, said member being vertically movable within said vessel between first and second positions, said member being in said first position removed from said apertured region of said sidewall when the apparatus is in a normal upright position and in said second position at said apertured region to cover the latter when the apparatus is in an inverted position.

3. The combination of a. a source of supply of air under pressure comprising a movable tank-type suction cleaner having an inlet and outlet for air, the outlet serving as the blowing and of said cleaner,

b. structure providing a housing adapted to hold a body of cleaning liquid possessing such physical properties that it will generate foam responsive to air bubbling therethrough,

c. surface contacting means which is carried by said housing structure and movable over a surface for distributing foam thereon,

d. an air line having an air inlet exteriorly of said housing and an air outlet within said housing at the bottom thereof,

e. means including a coupling for conducting air under pressure from the outlet of said cleaner to the inlet of said air line, such air being substantially free of dust removed therefrom in said suction cleaner,

f. means at the outlet of said air line for subdividing the substantially dust-free air under pressure to form air bubbles which rise through the body of liquid to generate foam,

g. vertically extending conduit means defining a passageway having its upper end in communication with the upper part of said housing and its opposite lower end communicating with said surface contacting means for flowing thereto foam from the upper part of said housing;

h. means forming a unitary part of said coupling for mounting the latter on said cleaner at the air outlet end thereof,

. said coupling constituting an independently movable component of the combination and being hollow and having an outer wall,

. said coupling having partition means including an axially extending partition to form first and second passageways at opposite sides thereof, each of said passageways being defined by the outer wall of said coupling and said partition means and having an inlet at the end of said coupling connected to the air outlet of said cleaner,

k. the cross-sectional area of said first passageway being greater than that of said second passageway and receiving a major portion of the air discharged from the outlet of said cleaner,

1. said first passageway in said coupling having an outlet for discharging said major portion of the air therefrom directly to the body of atmospheric. air enveloping said coupling, and

m. said second passageway in said coupling having an outlet,'the inlet of said air line being connected to the outlet of said second passageway to receive the lesser remaining portion of the air discharged from the outlet of said cleaner. 

1. Surface-cleaning apparatus comprising a. a source of supply of air under pressure comprising a movable tank-type suction cleaner having an inlet and outlet for air, the outlet serving as the blowing end of said cleaner, b. structure providing a housing adapted to hold a body of cleaning liquid possessing such physical properties that it will generate foam responsive to air bubbling therethrough, c. surface coNtacting means which is carried by said housing structure and movable over a surface for distributing foam thereon, d. an air line having an air inlet exteriorly of said housing and an air outlet within said housing at the bottom thereof, e. means including a bypass valve for conducting air under pressure from the outlet of said cleaner to the inlet of said air line, f. means at the outlet of said air line for subdividing the air under pressure to form air bubbles which rise through the body of liquid to generate foam, g. vertically extending conduit means defining a passageway having its upper end in communication with the upper part of said housing and its opposite lower end communicating with said surface contacting means for flowing thereto foam from the upper part of said housing, h. the inlet of said air line being connected to said bypass valve, i. said bypass valve having one passageway which receives a major portion of the air discharged from the suction cleaner outlet and diverts such air to the atmosphere and another passageway which receives the lesser remaining portion of the air discharged from the suction cleaner outlet and conducts such air to said air line, j. a valve in said air line, k. said valve including means defining a seat and a valve movable between a closed position at said seat and an open position removed therefrom, and l. said valve being in its open position when air under pressure is delivered to the inlet of said air line from the outlet of said suction cleaner, and, when the inlet of said suction cleaner inadvertently is connected to the inlet of said air supply line, said valve moving to its closed position responsive to flow of air in said air line toward the inlet end thereof.
 2. Surface-cleaning apparatus comprising a. structure providing a housing adapted to hold a body of cleaning liquid possessing such physical properties that it will generate foam responsive to air bubbling therethrough, b. surface contacting means which carried by said housing structure and movable over a surface for distributing foam thereon, c. an air line having an air inlet exteriorly of said housing and an air outlet within said housing at the bottom thereof, d. means connected to the inlet of said air line for delivering thereto air under pressure from a source of supply, e. means at the outlet of said air line for subdividing the air under pressure to form air bubbles which rise through the body of liquid to generate foam, f. vertically extending conduit means defining a passageway having a region at its upper end in communication with the upper part of said housing and its opposite lower end communicating with said surface contacting means for flowing thereto foam from the upper part of said housing, g. means associated with said air line for diverting and bleeding therefrom a portion of the air adapted to be supplied thereto under pressure from the source of supply, h. said vertically extending conduit means including an enlarged portion at its upper end which defines a vessel having a top cover and a sidewall which is apertured and constitutes said region in communication with the upper part of said housing, and i. a member of annular form within said vessel which is adjacent to said sidewall thereof, said member being vertically movable within said vessel between first and second positions, said member being in said first position removed from said apertured region of said sidewall when the apparatus is in a normal upright position and in said second position at said apertured region to cover the latter when the apparatus is in an inverted position.
 3. The combination of a. a source of supply of air under pressure comprising a movable tank-type suction cleaner having an inlet and outlet for air, the outlet serving as the blowing end of said cleaner, b. structure providing a housing adapted to hold a body of cleaning liquid possessing such physical proPerties that it will generate foam responsive to air bubbling therethrough, c. surface contacting means which is carried by said housing structure and movable over a surface for distributing foam thereon, d. an air line having an air inlet exteriorly of said housing and an air outlet within said housing at the bottom thereof, e. means including a coupling for conducting air under pressure from the outlet of said cleaner to the inlet of said air line, such air being substantially free of dust removed therefrom in said suction cleaner, f. means at the outlet of said air line for subdividing the substantially dust-free air under pressure to form air bubbles which rise through the body of liquid to generate foam, g. vertically extending conduit means defining a passageway having its upper end in communication with the upper part of said housing and its opposite lower end communicating with said surface contacting means for flowing thereto foam from the upper part of said housing, h. means forming a unitary part of said coupling for mounting the latter on said cleaner at the air outlet end thereof, i. said coupling constituting an independently movable component of the combination and being hollow and having an outer wall, j. said coupling having partition means including an axially extending partition to form first and second passageways at opposite sides thereof, each of said passageways being defined by the outer wall of said coupling and said partition means and having an inlet at the end of said coupling connected to the air outlet of said cleaner, k. the cross-sectional area of said first passageway being greater than that of said second passageway and receiving a major portion of the air discharged from the outlet of said cleaner, l. said first passageway in said coupling having an outlet for discharging said major portion of the air therefrom directly to the body of atmospheric air enveloping said coupling, and m. said second passageway in said coupling having an outlet, the inlet of said air line being connected to the outlet of said second passageway to receive the lesser remaining portion of the air discharged from the outlet of said cleaner. 